1. Field of the Invention
The present invention relates to structures for controlling and monitoring positions of movable switching elements in an optical switch, and more particularly to electrode structures for controlling and sensing angular positions of micro-machined micro-mirrors in an optical switching device.
2. Description of the Related Art
Increasing demands for high-speed Internet service and wireless communications are soon expected to outstrip current telecommunications capacity. Because optical fiber networks are capable of transmitting huge volumes of data at blinding speeds, telecommunications carriers are turning to optical fiber networks in an effort to meet future needs.
In order to implement tomorrow""s optical fiber networks, the telecommunications industry needs new optical devices that are inexpensive, efficient, and scalable to accommodate future optical telecommunications network expansion. Telecommunications providers prefer optical fiber networks that can be reconfigured quickly and efficiently. This gives the optical network the flexibility to accommodate growth and changes in future communications patterns. The ability to reconfigure quickly and efficiently also enables the network to restore failed communications by rerouting the communications to bypass the failure.
Optical fiber networks can be reconfigured at network nodes using optical switches to change the coupling between incoming optical fibers and outgoing optical fibers. Currently under development are optical switches that use movable micro-mirrors. These optical switches couple the optical signals between input and output fibers entirely in optical form, instead of converting the optical signals to electrical signals, switching the electrical signals, and converting the switched electrical signals back to optical signals.
To successfully operate such switches, the componentsxe2x80x94including fibers, lenses, and the micro-mirrorsxe2x80x94must be properly aligned and the angular position of the movable micro-mirrors must be precisely controlled. If the angular position of the movable micro-mirrors is off and/or if the other components are not properly aligned, some or all of the light from the input fibers will not reach the selected output fiber. At switching speeds necessary for today""s optical communication needs, a micro-mirror based switch must rapidly move a mirror into position on command with minimal slew (where a slope of a micro-mirror trajectory output curve is close to a theoretically predicted one). Mirror movement must also quickly settle at a desired position to avoid signal loss. Micro-mirror switch control systems should also be insensitive to perturbations that would otherwise affect mirror position and hold maximum input-to-output optical coupling over long time scales.
Thus, there remains a need in the art for optical switch structures that can efficiently translate electrical signals into micro-mirror actuation to provide quick micro-mirror positioning. There also remains a need in the art for optical switch structures that allow reliable sensing of micro-mirror angular position to precisely control a mirror""s movement and/or provide accurate position status, whether a mirror is in a static or dynamic state.
The present invention has been made in view of the above circumstances and has as an object to provide an efficient and reliable optical switch.
The present invention has another object to provide methods for controlling an optical switch.
One aspect of the present invention is a plurality of electrodes having elongated sidewalls that are used to control movable mirror elements.
Another aspect of the present invention is a plurality of concentrically arranged segmented electrodes.
Yet another aspect of the present invention includes a structure and method for providing control to a movable mirror assembly from a freestanding conductive structure.
Still another aspect of the present invention is a plurality of segmented sidewall electrodes used for sensing a position and/or positioning a movable mirror.
Additional aspects and advantages of the invention will be set forth in part in the description that follows, and in part will be obvious from the description, or may be learned by practice of the invention. The aspects and advantages of the invention will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims.
It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.